Do not log error when Service for Endpoints is not found

[tnqn]

It's possible that some Endpoints don't have Service. For example,
kube-scheduler and kube-controller-manager may use Endpoints for leader
election.

Signed-off-by: Quan Tian qtian@vmware.com

Fixes #3255

[codecov-commenter]

Codecov Report

Merging #3256 (a6d1122) into main (9809991) will decrease coverage by 6.80%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #3256      +/-   ##
==========================================
- Coverage   59.66%   52.85%   -6.81%     
==========================================
  Files         331      462     +131     
  Lines       28437    54628   +26191     
==========================================
+ Hits        16966    28872   +11906     
- Misses       9595    23270   +13675     
- Partials     1876     2486     +610     

Flag	Coverage Δ
e2e-tests	52.18% <100.00%> (?)
integration-tests	34.02% <ø> (?)
kind-e2e-tests	47.90% <100.00%> (+0.27%)	⬆️
unit-tests	41.35% <0.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...g/agent/controller/serviceexternalip/controller.go	80.82% <100.00%> (-0.04%)	⬇️
pkg/agent/cniserver/pod_configuration_linux.go	26.31% <0.00%> (-40.36%)	⬇️
pkg/controller/ipam/antrea_ipam_controller.go	48.71% <0.00%> (-31.57%)	⬇️
pkg/controller/networkpolicy/endpoint_querier.go	61.46% <0.00%> (-29.97%)	⬇️
pkg/controller/egress/controller.go	61.11% <0.00%> (-27.34%)	⬇️
.../registry/networkpolicy/clustergroupmember/rest.go	64.28% <0.00%> (-23.95%)	⬇️
pkg/agent/cniserver/ipam/antrea_ipam.go	55.55% <0.00%> (-23.62%)	⬇️
pkg/agent/cniserver/ipam/antrea_ipam_controller.go	56.30% <0.00%> (-23.46%)	⬇️
pkg/agent/util/ethtool/ethtool_linux.go	46.66% <0.00%> (-23.34%)	⬇️
pkg/controller/ipam/validate.go	57.14% <0.00%> (-22.86%)	⬇️
... and 425 more

[xliuxu]

Thanks for the explanation.

[tnqn]

/test-all